1. Field of Invention
The invention relates to a control circuit, and more particularly to a control circuit implemented in a desktop or laptop computer to operate an optical medium.
2. Related Art
Current commercially available optical record medium processing devices such as CD-ROM drives have various functions, operation speeds and specifications. An optical record medium processing device known in the art may be classified as two types of apparatus, e.g. a read only memory (ROM) type optical record medium processing device and a writable/rewritable (R/RW) type optical record medium processing device. A compact disc (CD) has a capacity smaller than that of a digital versatile disc (DVD). The optical record medium processing device is, for example, a CD-ROM drive, a CD-R/RW (CD-RW) drive, a DVD-ROM drive, a DVD-RAM drive, a DVD+RW drive, a Combo drive, a Slim ROM drive, a DVD-Multi drive, a DVD Player, a DVD−RW drive or a PS2/XBOX CD-ROM drive.
Current developments have increasingly turned the personal computer into a personal digital video/audio center with high audio-video performance. If the audio-video function can be carried out without booting the computer, it would be very convenient for use and would provide another important use for the computer.
A portable computer with a low power CD-Player, which is used in the control of the CD-ROM drive without booting the computer has been disclosed. A specific application through a switch module when the computer host is in power-off or power-saving status is also disclosed. The above improvements are applicable to laptop computers using a battery as the main power supply. Therefore, even when the computer is not powered, the battery still keeps supplying power to the subsystems.
However, the desktop computer is powered by means of a power supply that converts an alternating current to a direct current. If the computer is shut off, the power supply then cannot offer sufficient power to operate the computer. Therefore, the computer has to be powered on just for listening to music.